This invention relates to a stabilizer apparatus especially useful for a multi-trailer rig to avoid swaying, fishtailing and the like while aiding in maintaining alignment for proper tracking on the highway.
In addition to jackknifing, as often occurs between tractors and trailers, multi-trailer rigs, often fishtail or otherwise sway as a result of failure to track in a straight path. These tendencies to sway are exacerbated by wind as well as other conditions on the highway. Driving a multi-trailer rig is a strenuous task since intense concentration is required by the driver at all times to counteract the tendency to sway which can result in loss of control of the vehicle. In common practice, the connection between respective trailers is through a simple pivotal connection at each end of a wheeled dolly which acts as a pivoted link connecting the trailers. Heretofore, there were no forces other than alignment of the respective trailers and connecting parts for avoiding swaying and maintaining straight tracking.
A stabilizing device for a trailer having a base fixed to the trailer carrying a pivoted plate is illustrated in U.S. Pat. No. 4,706,984. A pair of transversely spaced cylinder assemblies are each connected on one end to the plate and on the other end to the trailer. A solenoid valve to the cylinder assemblies is closed when the speed increases beyond a predetermined level increasing resistance offered by the cylinder assemblies to turning of the trailer.
Heretofore, many efforts have been made to avoid jackknifing. Some of these efforts include the use of abutments carried by the trailer and positioned in the slot of the fifth wheel of the tractor as disclosed in U.S. Pat. Nos. 4,934,727, 4,790,556, 4,784,403 and 4,700,966 and U.S. patent applications Ser. Nos. 07/597,001 and 07/770,571 now both abandoned which are also in the name of the present inventor, Wallace H. Hawkins.
The apparatus and method of this application complement the stabilizing effects of anti-jackknifing apparatus by also controlling movement between multiple trailers and thus combining to exert a stabilizing effect on the entire rig.
It is also an important object of this invention to minimize swaying or fishtailing between multiple trailers in tractor trailer rigs maintaining straight tracking by exerting of forces between a front trailer and a wheeled dolly to maintain alignment between the trailers, even as during an emergency stop. Because of the double pivot of the short dolly, such would otherwise have a tendency to fold up when the force of the back trailer is pushed forward resulting in a major cause of misalignment.
Another important object of the invention is to avoid fishtailing and to stabilize multi-trailer tractor trailer rigs by exerting forces as a force couple on opposite sides between a front trailer and the dolly as by fluid motors and the like tending to bring back alignment and by means of pressure continue to exert a force to hold the dolly in alignment.
Another important object of the invention is to temporarily establish a rigid connection between a trailer and a dolly of a multi-trailer rig during backing by actuation of mechanical stops limiting the action of the fluid operated cylinders pivotally connected between the trailer and dolly.
While the stabilizer is described in terms of its special usefulness in a pair of cylinder assemblies controlling a dolly of a multi-trailer rig, other uses are contemplated. Description is further in terms of a two trailer rig, but such stabilizers are also useful as on a three trailer rig. Since the cylinder assemblies each work independently at all times to exert a force tending toward alignment a breaking down of one cylinder assembly would not prevent the other to continue to work effectively to maintain alignment. While it may be possible to maintain alignment using only one stabilizer, the use of two are preferable because of the desirability of exerting a force couple to control the dolly. Since the dolly is short, it is relatively easily controlled as compared to a trailer. Since the back trailer follows the dolly, it is not necessary to exert a direct force upon the trailer.